The need to develop a vaccine for AIDS has never been so urgent. Progress toward the development and testing of an efficacious HIV-1 vaccine continues at an accelerated pace with a broad array of new basic science concepts and strategies under evaluation at the pre-clinical level as well as a significant expansion in the Phase l/ll clinical testing of promising vaccine candidates. The next two years represents a period in vaccine development in which the 'pipeline' of candidate vaccines making the transition from pre-clinical to clinical testing is extremely rich. It is estimated that nearly 20 new Phase l/ll clinical vaccine trials will be enrolling participants during 2004 alone. At the same time, there is a need to foster the development of new vaccine strategies based on hypothesis-driven research in the laboratories of the world's leading scientists. Considerable efforts are underway to better understand both the genetic diversity and antigenic composition of the virus as well as the immune responses that may be capable of containing the virus and the complex mechanisms used by the virus to evade these responses. Rapid dissemination of new information from basic to applied science must continue on a bi-directional basis if progress toward an efficacious vaccine is to be sustained. It is essential that both bench scientists and clinicians form a solid partnership in this venture. The key to establishing and preserving such crucial alliances is a regular scientific forum that encourages an open and objective exchange of ideas and new information. In planning this meeting, we sought to cover a wide range of topics that span all aspects of HIV development and testing from basic science insights through Phase l/ll clinical vaccine testing. Particular emphasis will be placed on current scientific challenges to successful vaccine development as well as future prospects to meet these challenges. An important aspect of the meeting is the opportunity for graduate students and postdoctoral fellows to present their original data in a highly interactive, relaxed environment that stimulates open discussion with established, knowledgeable scientific leaders in the field. [unreadable] [unreadable]